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15 Genetic Diseases

2.
Great changes in medicine <ul><li>one of the biggest victories in medicine over the past 100 years is that infectious diseases have decreased dramatically, for example, smallpox was eradicated, poliomyelitis will soon be eradicated and pertusis , diphtheria , malaria , measles are diminishing </li></ul>

6.
Epidemiology of genetic diseases in China <ul><li>It is estimated that ,each year in China , there are 20,000,000 live birth neonates. 5% of them will suffer from inherited disorders or birth defects. it means that each year there are 1,000,000 new patients. </li></ul><ul><li>Over 10,000 kind of inherited diseases are found by now. </li></ul>

9.
Basic of genetics <ul><li>chromosomes exist in pair, so genes exist in pair. Paired genes could be divided into dominant gene and recessive gene. </li></ul><ul><li>traits are controlled by the genes </li></ul><ul><li>One gene one enzyme theory </li></ul><ul><li>the abnormal chromosomes and genes result in genetic diseases. </li></ul>

10.
Classification of Genetic Diseases <ul><li>Chromosomal abnormalities: including euploid ,21 trisomy, 45,XO(turner syndrome) and structure abnormal such as 5P- and 14 ring. </li></ul><ul><li>Gene diseases including single gene diseases such as PKU and polygenic diseases such as diabetes. </li></ul>

18.
DOWN SYNDROME <ul><li>First described by John Langdon Down in 1866, the syndrome is named after him. </li></ul><ul><li>in 1956, Tijo found human cell contained 46 chromosomes. </li></ul><ul><li>In 1959, Lejeune identified the underlying chromosomal abnormality of affected individuals having a additional #21 chromosome. </li></ul><ul><li>It is the commonest chromosomal disease. </li></ul><ul><li>Maternal age is linked to the syndrome. </li></ul>

19.
Manifestation of Down Syndrome <ul><li>Facial abnormalities:small head,recessed nose, small ears and mouth </li></ul><ul><li>mental retardation:IQ score less than 60 </li></ul><ul><li>development delayed ,short statue , obesity, fingers are short and stubby, simian crease on the palm </li></ul><ul><li>congenital heart disease and other malformations can be found in most cases. </li></ul>

21.
Classification of Down Syndrome <ul><li>Trisomy 21 (account for 95% of the individuals). </li></ul><ul><li>Translocation Down syndrome (4%) </li></ul><ul><li>Mosaic Down syndrome (1%) </li></ul><ul><li>translocation down syndrome don’t differ congnitively and medically from those with trisomy 21. but mosaic down syndrome is less severe because their trisomy cells are interspersed with normal cells. </li></ul>

27.
47 XYY Syndrome <ul><li>Karyotype is 47 XYY </li></ul><ul><li>The affected individuals are male in appearance, high and thin with increased tendency to be violent and so are more common in prison or to be a hero in wartime. </li></ul><ul><li>END </li></ul>

28.
Phenylketouria (PKU) <ul><li>Autosomal recessive disease </li></ul><ul><li>inborn error of metabolism </li></ul><ul><li>reason is the lack of phenylalanine hydroxylase or an essential co-factor(BH4) </li></ul><ul><li>mental retardation and seizure </li></ul><ul><li>dietary phenylalanine restriction in early infant is very important for mental development. </li></ul>